Technical Foundations: DIY Solar-Powered PC

Tom's drives a desktop PC including monitor with solar cells 24/7. In the first part of this project we focus on the technical foundations that underlie solar energy. After that, we dig into the necessary configuration of a solar-powered PC, including components and construction, along with a solar array composed of two modular panels. Pictures and video provide step-by-step instructions for construction and deployment. We invested a lot of sweat and enthusiasm in this project, and look forward to hearing from those who follow in these footsteps.

Interesting. One of my goals is to retire (in ~20 years) to a small house that gets most or all of its energy from solar and/or wind power; the rest perhaps coming from natural gas or other renewable source.

I have always wanted to do this. I don't see why the government (US) couldn't give people at least a 50% tax write off on all equipment related to solar or alternative energy installations. I think lots of people would go solar or otherwise. I know I would at least partial if not all.

Why was 1-2 gauge wire used? That seems kind of thick for a computer. I just used 6 gauge wire to power a 50amp range last week. Hope more details are to come like an itemized list of parts in future articles.

Taxpayers are allowed one credit equal to 30 percent of the qualified investment in a solar panel up to a maximum credit of $2,000, and another equivalent credit for investing in a solar water heating system. No part of either system can be used to heat a pool or hot tub.

Are you running your PC on 12v power with regulators or are you using an inverter?

Will clamp-on connectors work OK? Would solder connections work better? I would not risk loosing any energy accross a clamp or crimp connector.

Perhaps I did not understand the graphic but... how do I determine the correct orientation for a solar panel at any given point on earth?

I have a small solar cell but other than facing the panel towards the equator at some kind of an angle I have no idea how to orient it or how to adjust it throughout the year. I have seen lots of quotes for the correct angle at certain places during the summer, I want to know the correct angle for any given location at any given time of the year.

My small solar cell is successful so far generating a few watts per day which I use for recharging all of my AA and AAA Ni-MH batteries but I am reluctant to invest in a larger one until I know how to make it work at top efficiency.

Watts = Volts X Amps Energy is defined as the ability to do work. However in an electrical sense it is the amount of work done over a given period. Measured in Watt-hours it is obtained by using the following:

Well, finally something I can dig my teeth into - and possibly give some advice on to those that might think about doing something like this. I worked in this industry years ago, and continued with it years after as a hobby AND, I also have a RFC in to IEEE.

-First off, Solar is still and probably will always be a pipe dream until serious efforts to harvest, produce and increase the efficiency of solar cells. Fear not however, efforts are always under way and in many cases the prices are dropping on mass produced panels and work great in areas where sun is plentiful.

You need MANY days of FULL sun for solar to be worth while.

-Second, not many people understand how much power they use in their house. The average house would require more solar panels on their roof to produce enough power to become 'independent'.The cool thing about this is, many times you will produce more power than your batteries or usage will need depending on your area, amount of sun collected (efficiency of panels x quantity of panels). You can then tie into your electrical grid and 'push power' to the power company. Thus, in actual - earning money.

The cost of purchasing, installing and maintaining a solar array is VERY expensive in comparison to the costs of electricity for most.

Solar however, still - serves many purposes and at the very least is affordable TODAY to supplement a persons current electrical needs.

I love the discussion of 'green' energy. Which usually results in a discussion of the use of solar or natural gases.The usage of natural gas is not green. Research it, and you will find that there is much effort and much impact to using natural gas which in itself will eventually deplete. A good idea would be to get this from waste fills whereas they could produce 'some' gas that is usable for 'some' use of fuel in 'some' way...but that really is as far as NG goes as far as being 'green'.

Solar is definitely completely renewable. If you live in a sunny sunny area, it eventually will be worth it if you have a large enough roof or property 'footprint' unobstructed by trees and buildings......eventually.However...keep in mind that no trees means no oxygen. A large land footprint means building out and not up. Wasted land necessitating the need for more trees to go bye bye and thus - urban sprawl. Next - Solar as it is right now, just barely out of infancy really... is VERY harsh to produce. The energy to produce a solar panel (at least 5 years ago) at the average plant was amazing. It was the equal of knocking down an entire forest for a toothpick. There are also toxic by products produced many times in the making, coating and screen printing of the cells themselves.

I wont put you to sleep with the other logistics surrounding keeping up a system, batteries that eventually need tossed and replaced etc etc etc.

The only true 'green' energy is nuclear. Eventually the uneducated will realize this and let this happen, but until then we will continue to pollute our lungs with horrible chemicals that are also poisoning our waters for THOUSANDS of years. Nuclear, even with an accident - would only affect few...could be cleaned up and has the same results as far as air and water poisons as our current infrastructure. However, it would affect far fewer people. The problem is, who gets affected? The 'not in my back yard' thing..

Why was 1-2 gauge wire used? That seems kind of thick for a computer. I just used 6 gauge wire to power a 50amp range last week. Hope more details are to come like an itemized list of parts in future articles.

Probably to eliminate voltage drop because of how long the wire needs to be to stretch between the solar cells and the computer.

Interesting. One of my goals is to retire (in ~20 years) to a small house that gets most or all of its energy from solar and/or wind power; the rest perhaps coming from natural gas or other renewable source.

Seems very achievable.I just don't like some types of renewable fuel. Like putting corn in a car gas tank. Even if that works, That's good edible food!

The only true 'green' energy is nuclear. Eventually the uneducated will realize this and let this happen, but until then we will continue to pollute our lungs with horrible chemicals that are also poisoning our waters for THOUSANDS of years. Nuclear, even with an accident - would only affect few...could be cleaned up and has the same results as far as air and water poisons as our current infrastructure. However, it would affect far fewer people. The problem is, who gets affected? The 'not in my back yard' thing..

So - there's my 2 cents +

I read a lot about nuclear power. But what can be done with the waste? Also a better battery needs to be made to transport the power with no toxic waste(some kind of Ultra Super Capacitor)

Ok I have to put in my two cents...I started an alternative energy company and currently employ 3 engineers.We are focusing for the next few years on CPV (concentrated PV) and need some help. I don't want to highjack this thread but where else can I make this case?Anyway we need help with CPV panel supply...there is none that we know of, and those who do make them (SolFocus) are not talking.Look, what we do is deploy about 50MW of solar panels throughout cities...NOT ON ROOFTOPS. I cannot say where, but I can say no one is doing what we do.Anywho, I ask any of you interested in what we do, or know suppliers of CPV panels to PM me and we can talk.Let me now add to this thread. SOlar energy will NOT overtake nuclear, but be an alternative in smaller applications. The only company that can even come close to competing with the nuclear plants is Stirling ENergy Systems with an 85% (That's right 85%) efficient CSP model.No one for at least a decade will come close unless they copy the idea in China.So let us look to solar for alternative small applications and not as a replacement for nuclear. THey would eat us alive if they wanted to anyway, why risk it?Remember than ambient heat (Arizona) lowers solar PV efficiencies to almost half the rated amount, even down to zero on very hot days! So do not rely on what a manufacturer tells you. Trust ONLY NREL (national renewable energy labs), and even they may get it wrong from time to time. God help you if you do a search on their site for anything solar (you will get hundreds and thousands of articles, reviews, etc.) just sorting through them is a full time job!

Looong story short, solar is great, nuclear is here to stay (for a while) and I really need some help. 50MW per city people...imagine the greenhouse gasses we save, and the $$ we make (in Canada we get $0.42/kWh and 50MW in Toronto generates about 160GWH of electricity = $24M annually for the life of the units) any takers?

We created a new market and as such even BP SOlar, or Shell SOlar, or Kyocera, or Sharp (the big 4) cannot compete for another 5 years. But we NEED the CPV panels. We are not in the business of making them!

Please help and I again apologise for highjacking this thread. I am sure you will agree it is for a good cause (Clean Air, healthier Kids!).

The waste from nuclear is already being taken care of for the short term (ie less than 50 years). After about 50 or so years we will have the means to blast all this waste into space.

All it takes is a good politician and good legislation and the technology (space elevator anyone?). Same with the garbage but since there is not much incentive to get rid of garbage (which is growing exponentially) we will begin (as a species) with nuclear and toxic waste.

I have faith in the human race, we follow a simple formula:1. Make a mistake.2. Realize the mistake.3. Eventually fix the mistake.4. Find better ways ways of performing step 3.5. Repeat.

1. We made the mistake of thinking that steel drums will hold this waste (or whatever they put the waste in).2. We now know about this waste (the voting public).3. Once we have the ability, we will get rid of it.4. Once we can get rid of it cheaply, we are all happy!5. Make a new mistake haha!

i live in northern california and just installed a 4.3 kwh photovoltaic system. total came to about 33000 with 10000 rebate from state and 2000 credit from federal. all i can say is that i am extremely happy with the installation.

i have 4 PCs at home, 1 is a media/file server which is on 24/7. i cut my summer electric bill from $300 to NEGATIVE $60 on average for the past few months (i get credit from PG&E for energy that i produce and not use which will apply to my winter bill) the system will pay for itself in about 10 years and then free electricity for life (well i do have to pay a $7 a month "distribution charge")

i have no idea why more people dont want to do this. it's a win all around solution!

i really believe if you are going through the trouble of install panels, running the wiring, and all that jazz, you may as well install a larger system to power your whole house. the extra cost is just the solar panels, some additional installation, and an inverter.

just my $.02

PS to the poster a couple posts above - PV panels are in short supply all over the world - i had to wait 3 months for my installation just for the panels to be available. the panels i use are from sunpower - 21.5 advertised efficiency (realistically about 18%)

PPS to another poster - most panels are designed to stand up to 100mph wind load. but that depends on your mounting method. hail would damage it but that's not a big problem where i live.

PPPS the "best" orientation in north america is SW. there are many factors to consider such as shade, fog, roofline, etc. i have my orientated WNW due to physical limitation on my roof. thus, i converted to the E-7 time of use plan from PG&E which worked out beautifully.

ok my turn to put my '2 cents' in. I'm actually a solar engineer as in i've completed an bachelor of engineering majoring in solar power. I've cover all areas including actually manufacturing my own cells in a lab.

first up i'd like to respond the the guy saying nuclear is the only real green energy. This is so far from the truth in relation to waste product from the process as not only do the water and byproducts have to be stored but once the plant is decomissioned the entire plant has to be stored in exactly the same way as the waste. In big steel drums buried in a landfill somewhere, which incidentally will be uninhabitable (without serious health risks anyway) for at least 100 years. Not only is the waste generated vastly greater than any other fuel source the cost per kilowatt for power production is actually larger as well once you factor in cost of setting up, transportation of raw resources in and waste out and decommisioning of the plant, this must be factored in as it is the only true way to get an estimate of the cost of power.

ok my hat goes off to the toms hardware boys for trying this out and for actually doing it. but for an average user with a 500w power supply using a PC for 3 hours a day requires 1.5kW of power. at the 290W array they have produced it will require at least 5.1 full sun hours a day. now assuming that you have a tiltable sun tracking system (much more expensive to purchase and maintain, not to mention not feasible for many people) you will just about get that as the sun even if your tracking will only give a fraction of the percentage of full sun due to extra diffraction in the atmosphere, the same applies to winter when the sun is lower on the horizon and again travels further through the atmosphere.

To MPL with the 4.3 kw pv system i'm going to go out on a limb here and say that you use gas for your space and water heating as well as cooking . i'm also going to say your media pc is 400w and seeing as its on 24 hours a day thats 9.6kWh, thats almost 1/3rd of the power you generate on a good day. tip from me, turn it off if u ain't using it and watch your energy savings soar.

if you really want to save power around the house, ditch electric hot water and space heating and switch to gas, cooking can go either way but remember it takes 1 J of energy to heat 1ml of water 1 degree. so if your boiling 1L of water from 30degrees you are using 20W.

bornking when u acutally do what you are planning and can fill everyone else in i'd love to see what it is. The problems with CPV in open flat areas with high levels of incident sun and minimal levels of pollution, humidity and objects blocking the light are quite large and it would be interesting to see how you overcome them in a city eviroment.

"To MPL with the 4.3 kw pv system i'm going to go out on a limb here and say that you use gas for your space and water heating as well as cooking . i'm also going to say your media pc is 400w and seeing as its on 24 hours a day thats 9.6kWh"

yes, gas for space+water heating, and cooking. however, during the winter at night, we switch to electric space heater in our rooms (25' ceiling in the living room and our heater is not zoned - way too expensive to change for the lack of craw space under our house)

i used a powerangel to measure the amount of energy used on my media server and it is between 180-200 W depending on load. (huge fan of silence PC so i undervolt the CPU, 80+ power supply, etc.) i also have it to go to hibernate mode after 30 min of idle at which it uses about 2 W. beyond TV wakes it up automatically when it needs to record a show (and compress the files afterwards.) if i access the shared files via the PC, it also take about 20 seconds to wake up because of HD spin up time but i can live with that. thanks for the suggestions though, appreciate it.

Having erected two off-grid renewable energy using remote cabins I have learned form my mistakes. The other real breakthrough is the availability of hi-efficient pure sine wave inverters for an affordable cost.

If you allow my critics, I believe Tom´s crew is making a mistake using copper instead of aluminium as a conductive in the backbone. Copper is far more expensive. You just have to remember to use proper connectors when connecting aluminium to copper.

Use of high efficiency appliances is the key to everything. Special attention should be paid to cos fi factor, which is most often forgotten since normal households can mostly everywhere in the World ignore it.

Anyway my best advise is that have your system installed by a licensed electrician no matter the voltage. This applies to the whole house. Just use heavier cables (2,5 mm2) for 12 V lights and use PLC lights. Remeber in EU >50 VAC or >75 VDC requires a licensed electrician. The latter limit may be broken with serial connected solar panels. A good advise is to install cables yourself to a limit and let pros do the connecting job.

The essential part of the electric system should be wired to star-shape configration. Part of the wireing cabinet should be used for 12 V systems. A star configuration allows easy change from off-grid to grid systems should the grid power become available in the future. Trust me. It is very frustrating to get the grid next door just after you have finished your system.

Basic lights should be powered with battery power (12 V). There are 12 V elecrtonic ballasts available to operate standard industrial PL-tubes directly form the battery. This way you can turn your inverters off when you are absent which eliminates huge phantom loads (standby consumption). Still your lights remain active so you do not have to thumble in the darkness.

Most other household appliances should operate with local standard grid voltage and frequency procuced by the inverter. You will find out that all standard voltage equipment are clearly cheaper than 12 V systems. 12 V itself is very problematic since it has no allowance to voltage drops in cables. That means far cheaper cables and thinner cables are easier to install too.

With inverter you can use high power applications too eg. pumps. You can forget them with 12 V. It is likely that you find out that AC appliances have better efficiency too if you count cable losses too. This goes even with the inverter losses included.

24 V or 48 V would be nice. The problem is that there are not too many appliances available at that voltage.

With a large battery bank there should not be too many problems with your system. Inverter should be installed next to the batteries. Remember ventilation.

A good advise is to have a small combustion engine generator as a backup and to compensate peak consumption. There are combi inverter/chargers available which can adjust the charge current according to the consumption. This operates the generator the most efficient way.

Solar power is used to charge batteries only. A modern peak power tracking charge controller does it. System is ready for grid connection and it is very easy to upgrade by installing additional inverters or battery capacity.

I´m a MSc (industrial engineering) and have almost 20 yrs of work history in the facility management. Counry of origin Finland.

I think most outputs from a PC power supply are about 12v and 5v? Is it possible to use an alternative power supply for your solar PC that will take 12v in and split the output to 12v and 5v, thereby avoiding the inefficiencies involved in voltage conversion up to 110/240 and then back again to the lower voltages?

I think most outputs from a PC power supply are about 12v and 5v? Is it possible to use an alternative power supply for your solar PC that will take 12v in and split the output to 12v and 5v, thereby avoiding the inefficiencies involved in voltage conversion up to 110/240 and then back again to the lower voltages?

You can have 12Vdc power supply for your atx cabinet. You can even have 19” LCD-monitor for 12Vdc.And there are powersupply for 24Vdc, 48Vdc and110VdcI have one P4 for testing with110Vdc power supply and 17” LCD that have 110Vdc as well. The power supply are in range of 250-500W.

Where to buy ??........ that is the drawback. You probably end up by buying it from me.

I thought the article, and the subsequent forum posts, were both useful and interesting. Thank you very much.

I immediately clicked through to this article from my THG newsletter.

You see, I would like to build my own house eventually, with a few unique features. One of which is generating my power through solar, and having a facility to - say - store about a day's worth of electricity, (whilst also being connected to the grid, for a "backup").

So I'd use the power my solar panels generate, hopefully with some spare, as it may make me a bob or two. (I don't know what the UK's like for the latter...) Then, and here's the clever part, if the grid goes down for a while, and there's no sun that day, I can still continue working.

I have absolutely no knowledge of how this all works, but I'm guessing I'd need an exceedingly large (and expensive) battery - or set thereof - to do what I'm thinking.

If anyone wants to offer some cents - I mean sense - to what I'm saying, please feel free.

A good advise is to have a small combustion engine generator as a backup and to compensate peak consumption. There are combi inverter/chargers available which can adjust the charge current according to the consumption. This operates the generator the most efficient way.

Are there any companies out there who have seen this niche, ready to be filled by someone who develops and sells a highly efficient Stirling heat engine that runs off natural gas (or propane gas) at ~85% efficeincy instead of and ICE that burns gasoline or diesel at ~35% efficiency? I mean, it seems to me that this kind of purpose would be ideal for a Stirling engine, where instant high power is not nearly as important as efficiency and durability.

I thought the article, and the subsequent forum posts, were both useful and interesting. Thank you very much.

I immediately clicked through to this article from my THG newsletter.

You see, I would like to build my own house eventually, with a few unique features. One of which is generating my power through solar, and having a facility to - say - store about a day's worth of electricity, (whilst also being connected to the grid, for a "backup" ).

So I'd use the power my solar panels generate, hopefully with some spare, as it may make me a bob or two. (I don't know what the UK's like for the latter...) Then, and here's the clever part, if the grid goes down for a while, and there's no sun that day, I can still continue working.

I have absolutely no knowledge of how this all works, but I'm guessing I'd need an exceedingly large (and expensive) battery - or set thereof - to do what I'm thinking.

If anyone wants to offer some cents - I mean sense - to what I'm saying, please feel free.

There is a system at work in a small north London flat which may be a useful model to base your house on.The array produces around 700 watts at its peak, and the bank of 6 110 AH deep cycle batteries give a store of 7.2KWh. The occupier of the house is somehat frugal, getting consumption down to between 1 and 2 KWh per day.

The battery bank operates at 24 volts

The system is one of the ones linked from the sitewww.green-power-gen.org.uk,while a blogg gives regular updates on the system atcommunity.livejournal.com/green_power_gen

Interesting project. I myself are always looking for solutions to drive my Sound monitoring equipment independent from the grid. The very first choise to make is also the most simple: get yourself a notebook instead of a desktop! You will get a nice working system with an Energy consumption of 25 W or less!